The Sox announced Friday that Giolito, currently pitching with Triple-A Charlotte, will start one game of the doubleheader against the Twins at Guaranteed Rate Field on Monday, when the team is allowed a 26th player.

The Sox have not announced which game Giolito will pitch, and manager Rick Renteriadidn't reveal whether Giolito would stay in the rotation when they must send a player back to the minors.

Kopech will be promoted from Double-A Birmingham to Charlotte and will make his debut Monday at Norfolk, Va.

"(Giolito) is throwing a lot more strikes, using his secondary pitches very effectively," Renteria said. "I'm sure he's continuing to grow and get more comfortable in his own skin. It's basically confidence, repeating his delivery."

It will not be Giolito's major-league debut. He made six appearances including four starts with the Nationals last year, posting a 6.75 ERA before joining the Sox in the Adam Eaton trade in December.

Giolito is 6-10 with a 4.48 ERA, 134 strikeouts and 59 walks in 128 2/3 innings for Charlotte. He has found a groove in his last five starts (3-1, 1.71 ERA), including six scoreless innings with one walk and seven strikeouts Wednesday.

"He looked calm, collected and was dropping all of his stuff in there for strikes, which is the first prerequisite to come here," Cooper said. "He just got comfortable with what he's doing. His mechanics, he's all tall, back and closed. We are seeing that the result of that is more and more strikes to go along with the stuff he's got."

Kopech has been dominant in Birmingham, posting a 2.87 ERA with 155 strikeouts and 60 walks in 119 1/3 innings. In his last five starts, he has given up two earned runs with 49 strikeouts and five walks.

Charlotte's season ends Sept. 4, and the club has been eliminated from playoff contention, so Kopech, who was acquired from the Red Sox in the Chris Sale trade, would only make a few regular-season starts with the team.

Garcia still out: Sox right fielder Avisail Garcia missed a second straight game Friday with a sore left wrist he said he hurt while sliding earlier in the week against the Dodgers.

Garcia was named an American League All-Star after a strong first half, but he has dealt with minor injuries over the last two months to his knee, finger, thumb and wrist.

"I'm just erring on the side of caution," Renteria said. "He wanted to go out and hit early, and I said, 'Well, if it's calming down, let's give it another day. Keep getting treated, let me know tonight how you feel, and then we can make a determination about tomorrow's lineup.'"

Streak over: Nicky Delmonico went 0-for-4 Thursday, ending his Sox record 13-game on-base streak to open his career.